Hydraulic power actuator and pilot valve unit assembly



United States Patent [72] Inventor Marvin E. Whiteman, Jr.,

10010 Shoshone Ave., Northridge, California 91324 [21] Appl. No. 724,135[22] Filed April 25, 1968 [45] Patented Sept. 29, 1970 [54] HYDRAULICPOWER ACTUATOR AND PILOT Y VALVE UNIT ASSEMBLY 15 Claims, 3 DrawingFigs.

[52] US. Cl ..l37/625.66, l37/625.68. 137/625.69, 251/282 [51] Int. ClFl6k 11/07, Fl6k 39/04 [50] Field ot'Search 251/282; 137/596.12, 596.13,625.66, 625.67, 625.68, 625.69

[56] References Cited UNITED STATES PATENTS 2,294,702 9/1942 Van DerWerff 25 l/282X 2,363,235 11/1944 Ellinwood l37/596.l2X 3,229,721 1/1966Bingel 137/625.69

Primary Examiner-Henry T. Klinksiek Attorney-Wham and McManigalABSTRACT: Fluid powered actuator means in which a cylinder reciprocablycontains a piston connected to a power delivery element'and beingoperable b y a pressurized fluid such as water, oil and the like, thecylinder being fitted with end caps, one or both of which mounts a pilotvalve body having a bore therein containing a spool valve forselectively controlling flow paths between a plurality of fluid flowconnection ports, the spoolheing spring urged to one operating position,and mechanicallyactuated to another operating position by means of a camwithin the cylinder and which is supported for movement with the pistonand arranged to engage a roller carried by the spool valve. One end ofthe pilot valve bore communicates directly with the cylinder interior sothat the moving valve parts and cam are totally enclosed and lubricatedby the motivating fluid of the actuator. A passageway through the spoolvalve applies cylinder fluid pressure against opposite ends of the spoolso as to provide balanced operation thereof at all times.

HYDRAULIC POWER ACTUATOR AND PILOT VALVE UNIT ASSEMBLY BACKGROUND OF THEINVENTION The invention relates to a hydraulic power actuator which iscombined with a pilot valve to provide a unit assembly for controllingfluid control circuits in timed relation to the operation of the poweractuator.

Power actuator unit assemblies such as conceived in the presentinvention are susceptible of general use in any hydraulic control systemwhere it is desired to cycle the operation of a hydraulic power actuatorfor a particular device with the operation of a hydraulic power actuatoron another device. As exemplary of such an application, the invention isespecially useful in connection with concrete pumping apparatus such asillustrated in US. Letters Pat. No. 3,327,634, wherein the poweractuators of concrete pumping instrumentalities are operated in timedcyclic relation with respect to gating valves and other devices of thesystem. As it will be noted from this patent, the conventional procedurewas to utilize a separate pilot valve unit provided with an actuatingmember adapted to be motivated by means of a cam carried by or movablewith a part of the actuator unit such as the externally projecting partof the power delivery rod or element.

The pilot valve unit and associated cam, as heretofore'utilized, weremore or less openly exposed with respect to at least a portion of theirmoving parts. These exposed moving parts were easily susceptible ofcontamination and lacked proper provision for proper protection againstthe elements, or for lubricating internal parts. As a result,contamination, lack of lubrication and other factors inherent in theconventional ar-' rangements could easily function improperly and causea malfunction in the cyclic operation of the system devices.Malfunctions manifestly in concrete pumping systems and other batchingsystems might become exceedingly costly.

The above noted problem as well as others inherent in the presentlyknown conventional arrangements have to a great extent been eliminatedby the herein described invention by providing a unitized assemblywherein the cycling pilot control valve is intimately associated withthe power actuator in order to provide an integrated unit assembly,wherein the operatively associated moving parts of the actuator andpilot valve will be entirely enclosed, and in which the pilot valvemeans will be lubricated by the pressurized fluid medium utilized formotivating theactuator.

SUMMARY OF THE INVENTION The present invention relates generally tohydraulic power actuators, and is more particularly concerned with apower actuator unit having a built-in" pilot valve which is controlleddirectly in response to the operation of the actuator.

In its broad concept, the present invention seeks to provide a poweractuator unit, susceptible of general application, in which the actuatorand a cycling pilot valve operable in timed relation to the actuator arecombined so as to provide a combined unitized mechanism. Theaccomplishment of this purpose is obtained by constructing the pilotvalve as a part of an end cap of the actuator cylinder, with theinternal parts of the valve being arranged for direct actuation by a camof the actuator and so that the motivating fluid of the actuator willalso continuously lubricate the valve parts.

Having in mind the broad concept of the present invention, it is oneobject to provide a hydraulic power actuator and pilot valve as aunitized assembly wherein the pilot valve parts and its actuating meansare entirely enclosed, and will be continuously lubricated by themotivating fluid medium for the actuator.

A further object is to provide a hydraulic actuator unit according tothe foregoing object wherein the pilot valve is incorporated as a partof an end cap of the cylinder of the power actuator, the end cap havinga valve cavity in communication with the interior of the cylinder andproviding a space in which the coacting elements of the valve andactuator may operate,

and in which the valve means are balanced with respect to the pressureactuating fluid of the actuator.

Another object of the invention is to provide a valve structure as apart of a cylinder end cap structure which is so designed as to permit avalve to be positioned at one end of the cylinder or to permit valvesbeing positioned at opposite ends of the cylinder where it is desired tohave multiple valves operating in timed relation to the operating cycleof the power actuator.

Still another object of the invention is to provide a pilot valvestrpcture in the form of an end cap for use with hydraulically operatedactuators, and which will permit the end cap being produced as aseparate unit for adapting a conventional power actuator unit for cyclicoperation with other actuator units.

The foregoing and other objects, features and advantages of theinvention will be presented in the following part of the specification,wherein detailed description is for the purpose of fully disclosing theinvention without placing limitations thereon.

BRIEF DESCRIPTION OF THE DRAWINGS Referring to the accompanyingdrawings, which are for illustrative purposes only:

FIG. 1 is a fragmentary side elevational view of a hydraulic poweractuator and pilot valve unit assembly embodying the features of thepresent invention, portions being shown in sec- I DESCRIPTION OF THEPREFERRED EMBODIMENT Referring more specifically to the drawings, thepresent invention for illustrative purposes is shown in FIG. 1 ascomprising a hydraulic power actuator A and pilot valve B which havebeen combined according to the present invention into a unit assemblyfor use in systems utilizing a plurality of fluid actua- I tors, and inwhich it is desired to cycle the operation ofcontrol for certain of thedevices in dependence upon the operation of one or more of the hydraulicactuators.

The hydraulic power actuator A is of conventional construction in so faras it comprises a cylinder 10 having its ends mounted in an end capstructure 11 at one end and a power delivery end cap structure 12 atitsother end. These end caps are provided with suitable ports adapted forconnection with a supply conduit 13 in the case of end cap 11, andconduit 14 in the case of end cap 12. By means of these conduits,suitable actuator fluid pressure may be alternately admitted andexhausted to the cylinder for actuating an operatively associated piston15 therein for reciprocable movement, this piston being connectedwith apower delivery piston rod 16 which is carried through a suitable bushingin the end cap 12 where it is provided with appropriate coupling means(not shown) for connecting to the device to be operated thereby. Therods 17 interconnect the end caps and retain them in assembled relationwith the cylinder to provide the actuator assembly.

As will be seen, the power delivery end cap may be provided with asuitable attaching flange or flanges 18 for mounting the tended positionof the power delivery piston rod. Should it be I required that thesystem be so operated, a pilot valve may be positioned at both ends ofthe cylinder. It is believed that the operation of the pilot valve willbe fully comprehended from a description of a valve as mounted in oneposition only, for example, upon the end cap structure 11.

As shown in FIG. 1, the pilot valve comprises a hollow valve body 21 ofgenerally elongate construction having an internal axially extendingbore 22 which is in communication at its inner end with a bore passage23 formed in the end cap wall and having communication with an internalcavity 24, this cavity being axially aligned with the cylinder andhaving a communicating port opening 25 into the adjacent end of thecylinder.

Between the opposite ends of the valve body 21, the body is enlarged andinternally constructed to provide spaced cavities which are incommunication with corresponding port openings arranged for theconnection of fluid control conduits for the flow of pressurized fluidunder the control of the pilot valve. While any conventional arrangementmay be provided to control any practical number of flow lines, in thepresent instance provision is made for the connection of three conduitsby providing connection ports 26, 27 and 28 which communicate with acentral cavity 260, an inner cavity 27a and an outer cavity 28a, each ofthese cavities extending around the outer periphery of the bore 22.

Reciprocably mounted within the bore 22 is a spool valve 29, this valvehaving end portions 30 and 31 respectively in axially spaced apartrelation and being interconnected by a neck portion 32 of reduceddiameter. The end portions 30 and 31 are respectively slidably movablein bore portions 22a and 22b. The bore portion 22a extends below thecavity 27a, while the bore portion 22b extends above the cavity 28a. Thecavity 280 is separated from the cavity 26a by a wall portion containinga bore passage 22c, while cavity 270 is separated from the cavity 26a bya wall portion containing a bore portion 22d. With a valve spool as thusarranged, it is readily apparent that the valve can be moved to an upperposition wherein the connection ports 26 and 28 will be connected whilethe port 26 will be disconnected with respect to the port 27. On theother hand, the valve spool is displaceable to a lower position in whichthe port 26 will connect with the port 27, but will be disconnected withrespect to the port 28. Selectivity of flow is thus controlled betweenthe ports.

At the upper end of the valve body 21, as seen in FIG. 1, the bore 22communicates with a slightly enlarged bore extension 33 which is closedat its uppermost end by a screw plug 34. The bore extension 33 houses acompression spring 35, one end of this spring being in engagement withthe screw plug, while the opposite end is engaged over a retaining nut36 having threaded engagement with an end stud 37 formed on this end ofthe valve spool, the nut being used to retain a stop washer 38 forlimiting the downward movement of the spool under the urging of thespring. The stop washer is-arranged to abut an annular shoulder 39 atthe bottom of the bore extension 33.

The lowermost end ofthe spool valve is formed with a transverselyextending end slot 40 within which a roller 41 is supported for rotationupon an axle pin 42.

In the raised position of the spool valve, as shown in FIG. 1, it willbe noted that an edge ofthe roller extends into the cavity 24, and thatwhen the spool valve is urged by the spring 35 to the limit of itsmovement, the roller will be in a positionwithin the cavity 24 whereinit will be in the path of movement of a cam member 43 carried by andaxially in alignment with the piston 15. When the piston is moved to theright, as shown in FIG. 1, the cam member will be withdrawn from thecavity 24, and the spool valve is then free to be urged downwardly toone of its control positions. However, when the piston is moved in anopposite direction so that the cam member re-enters the cavity 24, a camsurface thereon, as indicated at 44, will engage the roller and move itto its other control position. As thus arranged, it will be clear thatthe actuation ofthevalve will be synchronized with movements of thepiston of the actuator. As previously mentioned, in some installationsit may be desirable to also actuate a pilot valve at the end of thepower delivery stroke of the actuator. In such case the pilot valveassembly would be incorporated as a part of the power delivery end cap12. The actual construction of the pilot valve may vary, but has beendisclosed herein as comprising the separate valve body 21 which issecured to the associated end cap by incorporating in the structuresuitable mounting flanges 45-45, as shown in FIG. 3, anchor bolts 46extending through these flanges into threaded engagement with threadedbores provided in the end cap. The axial position of the valve body maybe varied to meet different installation requirements by providing asuitable spacer member47.

An important feature of the present invention is that the actuator fluidalso serves as a lubricant for the pilot valve parts. This fluid beingpressurized acts on the lowermost end of the spool valve, and would tendto force the valve against the pressure of the spring 35 and thusproduce faulty operation. This is prevented by providing an equalizingpressure of fluid at the opposite end of the spool valve through apassageway which connects the source of fluid pressure with the boreextension 33. For convenience, this is accomplished by providing anaxial bore passage 48 which interconnects the spaces at the oppositeends of the valve spool and subjects end areas to fluid pressure whichbalances the valve spool so that the fluid pressure does not interferewith the spool operation. The bore passage 48 also serves as a bleed forthe bore extension 33 for fluid which could otherwise be entrappedtherein.

From the foregoing description and drawings, it will be clearly evidentthat the delineated objects and features of the invention will beaccomplished.

Various modifications may suggest themselves to those skilled in the artwithout departing from the spirit of my invention, and, hence, l do notwish to be restricted to the specific form shown or uses mentioned,except to the extent indicated in the appended claims.

I claim:

1. Hydraulic power actuator means, comprising:

a. a main power actuator cylinder and fluid pressure operablereciprocable piston therein connected with a power delivery element;

b. a pilot valve unit including a valve body having an elongate boretherein communicating with an inlet port and an outlet port;

c. valve means extending into said bore and being movable to positionsrespectively connecting and disconnecting a flow path between saidports;

d. means normally urging said valve means to one of said positions: and

e. means including a part movable within said main power actuatorcylinder for actuating said valve means to the other of said positionsin response to the movement of said main power. piston to apredetermined position, whereby the pilot valve means operation iscontrolled by and in timed relation to the operation of the main poweractuator.

2. Power actuator means according to claim 1, wherein said bore has oneend in communication with the interior of said main power actuatorcylinder and the piston actuating fluid pressure therein, and said partcomprises a cam member.

3. Power actuator means according to claim 2, wherein said valve meanscomprises a valve spool axially reciprocable in said bore; and a flowpassage connects with the opposite ends of the spool for applying saidpiston actuating fluid pressure against balancing areas at the oppositeends of said spool and bleeding fluid from the outer of said balancingareas during movement of the valve means responsive to the pistonmovement.

4. Power actuator means according to claim 3, wherein said flow passage,extends between said areas through said spool.

5. Power actuator means according to claim 1, wherein the valve means inthe position disconnecting the flow path between said ports. connectsone of said ports into a flow path including a third port.

6. A hydraulic power actuator unit assembly comprising:

a. a cylinder and fluid pressure operable reciprocable piston thereinconnected with a power delivery element;

b. an end cap at one end of said cylinder;

c. a valve body carried by said end cap, said body having a plurality offluid flow connection ports;

d. valve means in said body supported for movement to differentpositions for controlling fluid flow between said ports; and

e. means responsive to piston movement for moving said valve means at apredetermined position of said piston.

7. A power actuator unit assembly according to claim 6, wherein thevalve means includes a valve spool member reciprocable within a valvebore having one end in communication with the interior of said cylinder.

8. A power actuator unit assembly according to claim 7, including a flowpassage for subjecting opposite end areas of the valve spool to theactuating fluid pressure in said cylinder, whereby the valve spool isaxially balanced.

9. A power actuator according to claim 8, wherein the flow passageextends through the valve spool between said end areas.

10. A power actuator unit assembly according to claim 7, wherein saidvalve spool is axially spring urged in one direction and said means formoving said valve means is operative to axially move said spool in anopposite direction.

11. A power actuator unit assembly according to claim 7, wherein thevalve bore communicates with the cylinder through a cavity in said endcap; the valve spool has an end extending into said cavity; and themeans responsive to piston movement includes a cam member engageablewith the spool end in said cavity.

12. A power actuator unit assembly according to claim 11, wherein thevalve spool end carries a roller positioned in the path of travel ofsaid cam member.

13. The combination with a fluid operable power actuator having acylinder and associated piston, of a pilot valve assembly-for mountingon said cylinder, comprising:

a. an end cap member adapted for sealed mounting at one end of theactuator cylinder, said member having a cavity open at one side adaptedfor communication with the associated cylinder interior;

b.. a valve body mounted at one side of said end cap, said body havingan.elongate bore with one end in communication with said cavity, saidbore having a plurality of flow connection ports;

c. a valve spool'reciprocable in said bore and adapted to be movedin"a-direction away from said cavity in response to movement of theactuator piston to control fluid flow between said flow connectionports, said spool having an end portion extending into said cavity; and

d. a spring normally urging the spool valve in the direction of saidcavity.

14. The combination according to claim 13, including a member rotatablysupported on said valve end portion.

15. The combination according to claim 13, wherein the valve spool hasan axial bleed and pressure equalizing passage extending between itsopposite end faces.

